Hollow ZnO from assembly of nanoparticles: photocatalytic and antibacterial activity

Hollow shells of ZnO were formed by the assembly of nanoparticles using PEG 400 wherein PEG-400 acted like both a solvent and a structure directing agent. The structure, morphology and optical properties were characterized by using PXRD, SEM, TEM and absorption studies. The hollow shells were found to possess high crystallinity with a surface area of 8 m² g^?1. The assembly was formed by nanoparticles ranging from 50 to 60 nm, whereas the size of the hollow shell ranged from 500 nm to 1 micron. Photocatalytic activity of these nanostructures was studied using Rhodamine B (RhB) and methyl orange (MO). Nearly 99% of the RhB dye was found to be degraded in 60 min while for MO, the degradation was 97% in 50 min. The pseudo-first-order rate constant was calculated as 0.072 min^?1 for the degradation of RhB and 0.075 min^?1 for the degradation of MO. The hollow shells were found to exhibit significant bacterial inhibiting efficacy at a low concentration of the particles. Comparative studies were carried out for photodegradation of Rhodamine B dye and antibacterial activity using spherical particles of ZnO and assembly of particles to form rods of ZnO. The results indicated that these hollow nanostructures could be used as a potential catalyst for the removal of dyes from water and as an antibacterial agent.